1. Field of the Invention
The present invention relates to isolated nucleic acid sequences encoding polypeptides having cellobiose dehydrogenase activity. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as recombinant methods for producing the polypeptides.
2. Description of the Related Art
Cellobiose-oxidizing enzymes were first described in the extracellular enzyme system of the white-rot fungus Phanerochaete chrysosporium (Westermark and Eriksson, 1974, Acta Chem. Scand. Ser. B 28: 204-208; Westermark and Eriksson, 1974, Acta Chem. Scand. Ser. B 28: 209-214; Ayers et al., 1978, European Journal of Biochemistry 90: 171-181). The cellobiose-oxidizing enzymes from this fungus have been identified: one is a flavoprotein called cellobiose:quinone oxidoreductase (E.C. 1.1.5.1) suggested to be involved in lignin degradation, and the other is a haemoflavoprotein called cellobiose dehydrogenase (E.C. 1.1.99.18) proposed to be preferentially involved in cellulose degradation.
Cellobiose dehydrogenases have also been found in the brown-rot fungus Coniophora putena (Schmidhalter and Canevascini, 1992, Applied Microbiology Biotechnology 37: 431-436) and soft-rot fungi such as Monilia sp. (Dekker, 1980, Journal of General Microbiology 120: 309-316), Chaetomium cellulolyticum (Fahnrich and Irrgang, Biotechnology Letters 4: 775-780), Myceliophthora thermophila (Coudray et al., 1982, Biochemical Journal 203: 277-284), Sclerotium rolfsii (Sadana and Patil, 1985, Journal of General Microbiology 131: 1917-1923), and Humicola insolens (Schou et al., 1998, Biochemical Journal 330: 565-571).
The cloning of the Phanerochaete chrysosporium cellobiose dehydrogenase gene has been disclosed (Raices et al., 1995, FEBS Letters 369: 233-238).
It is an object of the present invention to provide alternative isolated nucleic acid sequences encoding polypeptides having cellobiose dehydrogenase activity.